1. Field of the Invention
The present invention relates generally to glucosylated steviol glycoside compositions and methods for making and using them as a taste improver and flavor modifier in various food and beverage products. The invention also relates to a combination of selective combination of glucosylated steviol glycoside components and steviol glycoside molecules from Stevia rebaudiana Bertoni plant extract to make the optimum sweetness profile and flavor modification in food and beverage applications. The invention also relates to the combination of the steviol glycoside derived molecules and maltodextrin derived from starch to provide the mouthfeel and flavor modification characteristics of Glucosylated steviol Glycosides in reduced or no sugar added food and beverage products.
2. Description of the Related Art
The extract of Stevia rebaudiana plant contains a mixture of different sweet diterpene glycosides, which have a single base—steviol and differ by the presence of carbohydrate residues at positions C13 and C19. These glycosides accumulate in Stevia leaves and compose approximately 10%-20% of the total dry weight. Depending on the variety of Stevia plant, the major steviol glycoside molecules present in the stevia extract are stevioside, Rebaudioside A, Rebaudioside C, Dulcoside A, Rebaudioside D, Rebaudioside B and Rebaudioside F. Other minor components are Rebaudioside E, Steviolbioside and Rubusoside. Recent research found additional steviol glycoside molecules (Ohta et al, 2010; Prakash et al, 2013): Rebaudioside G, H, I, J, K, L, M, N, and O.
All steviol glycoside molecules have high intensity of sweetness, ranging between 50 to 400 times sweeter than sugar. However, apart from the high level of sweetness, they have also intrinsic properties of bitter and licorice taste and undesirable aftertaste. Some undesirable taste characteristics of glycosides can be as a result of contamination of other substances present in stevia extract.
One of the main ways to improve the taste quality is the enzymatic glycosylation of mixture of semi-purified steviol glycosides. It is known that the undesired taste attributes can be substantially reduced or eliminated by the reaction of intermolecular transglycosylation of various enzymes, upon which the attachment of new carbohydrates at positions C13 and C19 of steviol glycosides takes place (FIG. 1). With an increase in the number of glucose units in steviol glycoside molecules (for example, from stevioside to Rebaudioside A), the sweetness intensity increases and sweetness profile (taste) improves. However, the relative sweetness does not increase significantly beyond a certain level with a further increase of glucose units, as shown in FIG. 2. The published data show that the sweetness quality improves with the addition of glucose units, but does not explicitly or implicitly mention that the addition of glucose units contributes to a reduction of sweetness.
In this invention, a process is developed to make a mixture of glucosylated steviol glycosides with small amount of other steviol glycosides and maltodextrin. The process involved precise control of pH, temperature, enzyme source and activity, quality of stevia extract, glucose-donor (amount and source) and time to achieve blends of different ratios of glucosylated steviol glycosides, steviol glycoside molecules, and maltodextrin.